French foreign affairs minister Jean-Marc Ayrault called on Tuesday for an immediate United Nations Security Council meeting to discuss the situation in the Syrian city of Aleppo, which has been devastated by fighting.

“More than ever before, we need to urgently put in place means to end the hostilities and to allow humanitarian aid to get through unhindered,” Ayrault said in a statement.

The Syrian army and its allies announced the capture of a large swathe of eastern Aleppo from rebels on Monday in an accelerating attack that threatens to crush the opposition in its most important urban stronghold.

Capturing eastern Aleppo would be the biggest victory for President Bashar al-Assad since the start of the uprising against him in 2011, restoring his control over the whole city apart from a Kurdish-held area that has not fought against him.